Protective equipment



March 28, 1939. 3 w YL 2,152, 47?

PROTECTIVE EQUIPMENT Original Filed Aug. 14, 1955 3 Sheets$heet lInventor: George W. Eglern is Attorngy- March 28, 1939.

G. W. FYLER PROTECTIVE EQUIPMENT 3 Sheets-Sheei; 2

Original Filed Aug. 14, 1935 Inventor: George wggle His Zttorneg.

G. W. FYLER March 28, 1939.

PROTECTIVE EQUIPMENT Original Filed Aug. 14, 1935 3 Sheets-Sheet 3 k w 0mE MW 2 5 m m WW w Patented Mar. 28, i939 UNITED STATES SearchPROTECTIVE EQUIPMENT George W. Fyler, Stratford, Conn., asslgnor toGeneral Electric Company, a corporation of New York Application August14. 1935, Serial No. 36,157

Renewed December 31, 1938 18 Claims.

My invention relates to protective apparatus and more particularly toapparatus for protecting the individual units of electrical apparatus ofa multiunit system from faults while maintaining in service those unitsof the system which are free from fault.

While my invention is not limited thereto I contemplate its use moreparticularly in connection with high frequency apparatus such as carrierwave signal transmitters and amplifiers. It has for one of its objectsto provide a novel and improved form of protective system for suchapparatus.

In connection with high power broadcast transmitters, such as are usedfor radio program broadcasting, the continuity of service of thetransmitting equipment is of extreme importance. If, by reason of afault in an apparatus unit, such as an amplifier of said equipment, thetransmitter cannot be continued in service at its normal rated capacity,it is important to continue it in service at lower than normal capacity.In this way a large portion of the total area served by the transmittermay be afforded service which is substantially free from interruptionsdue to faults in the transmitter equipment.

In copending application Serial No. 36,752, filed August 17, 1935, forE. A. Leach and which is assigned to the same assignee as my presentapplication, is shown a high frequency transmitting system in which theindividual operating units may be disabled and removed from service inresponse to a fault therein while the remainder of the equipment iscontinued in service. Thus, for example, the transmitter may comprise aplurality of amplifiers any one of which may fail at any time. Means areprovided automatically to remove an amplifier in which a fault occursfrom service and to establish connections whereby the other amplifiersare continued in service.

My present invention relates to systems of the type illustrated anddescribed in the said application of E. A. Leach and it has for one ofits objects to effect certain improvements in such apparatus whereby itis rendered more practicable.

A further object of my invention is to provide means whereby, while thedifferent operating units are individually protected from instantaneousfaults occurring therein, they are selectively removed from service onlyin dependence upon the nature of the fault. That is, they are removedfrom service, for example, if the fault be of greater than apredetermined duration or recurs within a predetermined interval. Inthis way, in accordance with my invention, removal from service of aunit in response to faults of a transient nature is avoided while at thesame time i the unit is protected from such a fault by being deenergizedin response thereto and for the duration of the fault, and then isautomatically restored to service.

In connection with equipment of the type referred to, there are certainapparatus units, such as power supply equipment, and audio amplifiers,which are essential to any operation of the system. One of the objectsof my invention is to provide means whereby in response to a fault ofeither the continuous, or recurrent character referred to, in such unitsthe entire apparatus is deenergized.

Still another object of my invention is to prevent deenergization ofcertain of the operating units which are free from fault in response toa fault condition produced in the power supply equipment by reason of afault which exists in an operating unit supplied with power thereby.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My inventionitself, however, both as to its organization and method of operation,together with further objects and advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawings in which Figs. 1, 2, and 3 taken togetherrepresent an embodiment of my invention.

These drawings may best be read by placing Fig. 1 at the left of Fig. 2and Fig. 3 below Fig. 2 and spaced to align the lines extending fromFig. 2 to the other figures.

General The drawings represent my invention as applied to a highfrequency signal transmitter having three output high power amplifiersindicated by the rectangles A1, A2, and A3 on the drawings, and twomodulators M1 and Ma. The amplifiers A1, A2, and A3 are excited withhigh frequency oscillations supplied thereto by an exciter I, the inputto each of the difierent amplifiers being connected across the outputcircuit 2 of the exciter for parallel operation. The output circuits ofall of these amplifiers are connected in a series circuit extending fromantenna 3 to ground 4, which circuit may readily be traced on thedrawings but which will later be described. Anode potential foroperation of all the amplifiers as well as the modulators M1 and M: issupplied by a rectifier 5. Similarly bias potential for all of theseunits is supplied by a bias supply system 6.

Signals to be transmitted are impressed upon line conductors I amplifiedby low power audio amplifiers 8 and supplied to the input of high poweraudio amplifier 9, the output of which is .supplied through a conductorID to the input of each of the. modulators M1 and M2.

All of the amplifiers A1, A2, and A: and the modulators M1 and M: areconnected in operating Roon circuit relation with each other and haveoperating potential supplied thereto through respective portions of acommon isolation switch mechanism indicated on the drawings directlyabove the rectangles representing these amplifiers and modulators. Bymeans of this switch mechanism and the control circuits providedtherefor, which will later be described, any one of these units may beautomatically removed from service in response to a fault occurringtherein while the remainder of the units are continued in service. Inresponse to an instantaneous fault in any unit means are providedwhereby all of the units are deenergized for the duration of the fault.If the fault, however, persists for more than a predetermined interval,or if it recurs within a predetermined time, even though the originalfault and its recurrence be but instantaneous, the respective unit inwhich the fault occurred is automatically removed from service by theswitch mechanism. Faults may likewise occur in the rectifying apparatus5 and in the audio amplifier 9 as well as in the bias supply system forthe different amplifiers. Means are also provided whereby a persistentor repeated fault in either of these units causes power to be removedfrom the entire apparatus.

Switch structure Having now very generally indicated the'character ofsystem to be described, I shall first describe more in detail the switchstructure shown in Figs. 1 and 2 whereby the desired isolation of thedifferent units is effected. I will then describe in detail the circuitsin which this isolation switch is connected, and later explain theoperation thereof. v

This isolation switch comprises a number of sections each of whichcontrols the circuits of a respective apparatus unit A1, A2, A3, M1, M2,these sections being indicated on the drawings by the brackets andreference characters of the respective apparatus unit preceded by theletter S. All of the cliiferent sections of the switch may be alike inconstruction and are represented by similar conventions on the drawings.Accordingly, I shall describe but a single section and will referparticularly to section SA1. This section, it will be observed,comprises a sleeve l2 arranged for rotation on a shaft l3. This shaft l3extends throughout the length of the switch and the sleeves l2 of all ofthe different sections of the switch are arranged for rotation thereonand, of course, are suitably spaced in accordance with the position ofthe different apparatus units which are controlled by the respectivesection of the switch. Each of these sleeves has mounted thereon threenon-conducting cross-arms I4, l5, and I6 each of which corresponds witha respective bank of six spaced contacts, these contacts in each of thedifferent banks being designated by the letters a to ,1 respectively.Each crossarm has mounted at each of its opposite ends a conductingbridge member l4, l4"; l5, l5"; l6, l6"; these conducting bridge membersbeing arranged when the switch is in its normal condition, which is thatshown in the drawings, to bridge a pair of contacts in the respectivecontact bank. For example, each of the bridge members l4, l5, l6 areshown as bridging the contacts a and b of its respective bank, whereasthe bridge members If", I5", and [6" are shown as bridging the contactsd and e of its respective bank.

It will be noted that the contacts of each bank are arranged in acircle, the contact 0 being positioned between contacts b and d, and thecon-;

tact 1 being positioned between contacts 0 and IB" bridge contacts 0 andd of their respective banks. To effect this rotation of the sleeves l2in each section of the switch a suitable actuating mechanism I1 isprovided. While this mechanism may be of any suitable type, I prefer toemploy a mechanism of the type shown, for example, in United StatesPatent No. 7,935,432 issued November 14, 1933 to Lawrence Bourst andentitled Electrohydraulic operating mechanism. Such a mechanism iscommonly referred to as a Thrustor.

This mechanism comprises a motor operated pump which forces a suitablefluid, such as oil, from one side of a piston to the other, therebyactuating the piston in a certain direction. The return stroke of thepiston may be caused by external force applied to the piston or by meansbiasing the piston to the normal position, the return movement beingclamped by the flow of oil through an orifice back to the original sideof the piston.

The member I8 is reciprocated by the piston of the Thrustor and isattached to a lever 19 at an intermediate point thereof. This lever ispivoted at the point 22 and is connected at its opposite end through anintermediate member 23 to an arm 24 which is attached to the sleeve 12.Thus when the Thrustor I1 is energized and its member [8 is actuatedupwardly, the sleeve i2 is rotated about the rod I3 thereby carrying thedifferent cross-arms to a position such that the bridge members l4, l5,16' engage the contacts w and f of their respective banks, and similarlythe bridge arms [4", l5", and i6" bridge contacts 0 and d of theirrespective banks.

The upper end of the intermediate member 23 is also connected to the endof a lever 25 which is pivoted at its opposite end. A switch member 26carrying a number of movable switch contacts 21, 28 and 29 is connectedto an intermediate point on the lever 25 whereby the contacts carried bythis member are reciprocated between different positions in accordancewith the rotation of the sleeve l2. The purpose of these contacts willlater be indicated.

The return of a section of the switch from the alternate position to thenormal position is eifected at a time when the rotator I1 isdeepergized, the rotation being caused by the bias of the piston of therotator, aided, if desired, by spring 45 shown on the drawings.

It is necessary, however, prior to any rotation of any section of theswitch that the movable contacts thereof be first disengaged from therespective stationary contacts, and further, that the rotation shall becompleted prior to reengagement of the movable contacts with therespective stationary contacts. At least, pressure between thestationary and movable contacts should be removed before any rotarymovement occurs and should be reapplied only after the rotary movementis completed. To effect this operation of the different sections of theswitch the rod l3, which extends through all of the sections, isarranged for longitudinal movement and to carry therewith the movableelements of all of the difierent switch sections. Thus when shaft i3 isactuated to the right, the movable contacts of all the switch sectionsare operated to the right into disengaged relation with the stationarycontacts. Any one or more sections of the switch may then be rotated tothe alter nate position when theshaft l3 may again be actuated to theleft bringing the movable contacts into engagement with correspondingstationary contacts. When in the alternate position this engagement ofthe contacts retains the switch in position since the bias of the pistonand spring 45 are insufficient to overcome friction between thecontacts.

To effect this actuation of shaft l3 it is biased to the right by meansof a spring 32 attached to the right end of the rod l3. The left end ofthe rod is attached at a point 33 to a cam 34. This cam is arranged forrotation about the pivot 35 above the point 33 whereby as the cam isreciprocated about this pivot it causes reciprocal longitudinal motionof the rod !3. The cam is restrained in the position shown against thetendency to counterclockwise motion under influence of the spring 32 bymeans of a latching device 36. This latching device has a roller 31which normally lies behind a shoulder 38 of the cam whereby the cam isrestrained against counterclockwise rotation.

The latching device 33 is attached to the armature of a latch magnet 39whereby when this magnet is energized the latch is lifted to release thecam and the cam is then rotated under influence of the spring 32. If themagnet be then deenergized, the roller 3'! falls upon the periphery ofthe cam and is thus held in an upward position. If the cam be nowrotated in a clockwise direction to its final position, which is thatshown in the drawings, the latch 36 again falls, the roller 31 droppingbehind the shoulder 33 and restraining the cam in the position shown. Toefiect clockwise rotation of the cam an actuating mechanism 42, whichmay be of the same type as the actuating mechanism I1, is provided, thisdevice being attached to the cam at the point 43 whereby when its pistonactuated member 43 is operated upwardly the cam is rotated in acounterclockwise direction.

It will be understood that all of the mechanisms H and 42 serve animportant function not only when energized to effect rotation of therespective section of the switch, or the cam 34, but also whendeenergized to permit opposite rotation of the respective elements ofthe switch under influence, for example, of spring 45 or 32. Theirfunction when deenergized is to damp the motion of the spring by reasonof oil within the Ihrustor flowing through an orifice, as previouslyexplained, thereby to avoid abrupt, violent, or jerky, motion of any ofthe switch members, likely to impair any portion of the mechanism.

It will be observed that each section of the switch is provided with itsrespective auxiliary switches 21, 28, and 23. Certain additionalauxiliary switches common to the entire switch are also useful ineffecting its desired operation. Certain of these auxiliary switchescomprise the armatures 46 and t! which are connected at one end of alever 48 which is pivoted at 49, the opposite end being connected to thearmature of the latch magnet 39 whereby these switches are. actuated inaccordance with the energization of the latch magnet. These switchesopen when the latch magnet is energized and close only when the magnethas been deenergized and the roller 3'! falls behind shoulder 38 of thecam. An additional auxiliary switch 52, which may be of the tumblertype, is actuated in accordance with the position of the cam 34. Thisswitch has a control member 53 which is straddled by the bifurcated endof a lever 54 which is pivoted at an intermediate point 55. The oppositeend of the lever is attached by rod 56 to a suitable point on the camwhereby the left end of the lever 54 israised and lowered as the cam 34is rotated. Thus when the cam rotates in a counterclockwise directionthe control member 53 is raised to close the switch, and when the cam isrotated in a clockwise direction the member 53 is lowered to open theswitch. The arrangement is such that the contacts of switch 52 areclosed early in the counterclockwise rotation of the cam 34 and theyremain closed until late in the clockwise rotation thereof.

An additional auxiliary switch 51, likewise of the tumbler type, andhaving a control member, or handle 60, is provided, together with meansproperly to time its operation with that of movement of the cam. Thismeans comprises a rack made up of a pair of parallel bars 58 connectedtogether, somewhat in the manner of the side rails of a ladder, andarranged for motion longitudinally of themselves upon a pair of supports59 which extend through longitudinal slots in the ends of the parallelmembers. The control member of switch 51 is preferably positionedbetween rungs of the ladder to be operated upwardly and downwardlythereby, but for clearness of illustration is shown as operated byprongs 6| projecting from one of the side rails of the ladder. Thisladder comprising the bars 58 is arranged to be operated upwardly bymeans of a tail member 63, which is attached to the cam 34 andpositioned to engage one of the rungs of the ladder during thecounterclockwise motion of the cam and to lift the ladder to such aposition that the lower prong 6| engages the handle 60 of the tumblerswitch and causes the switch to close late in the counterclockwisemotion of the cam. During the clockwise motion of the cam the tailmember 63 moves downwardly but the ladder remains suspended by upperprong 6| engaging the member 60 since the weight of the ladder is notsufficient to operate the tumbler switch 63, which is, of course, springbiased to both positions and arranged for snap action as by means of atoggle. When the cam 34 reaches its final position, however, and roller3'? on latch 36 drops behind shoulder 38 of the cam, a member 62 carriedby the latch falls upon a rung of the ladder with suiiicient force toforce it to its lower position causing the switch 59 to open itscontacts.

Amplifier circuits I shall now proceed to describe the circuits in whichthe switch structure already described is connected. In the first place,the amplifiers A1, A2, and A3 may be of any suitable construction. Theseamplifiers may, for example, comprise a pair of electron dischargedevices 64 connected in push pull relation, the grids being connectedtogether by means of a suitable inductance coil 65 and the anodes beingconnected together by means of a tuned circuit 66 to which is coupled anoutput coil 61.

As previously stated, the inputs of the different amplifiers are excitedin parallel from the exciter I. This circuit for the amplifier A1extends from the output circuit 2 of exciter l through conductor 68,bridge member I6" of section SA1 of the switch in its normal position,and conductor 69 to one terminal of the inductance coil 65 and thencefrom the opposite terminal of this coil through conductor 12, bridgemember I5 of section SA1 of the switch, and conductor I3 to the oppositeside of the output circuit to exciter I. A similar circuit for each ofamplifiers A2 and A.'; may also be traced on the drawings.

As previously stated, the outputs of each of the different amplifiersare connected in series between antenna 3 and ground 4. This circuitextends from ground 4 through conductor I4, bridge member I4 of sectionSA1 of the switch, conductor I5, output 61 of amplifier A, conductor I6,bridge member I4", conductor I1, bridge member I4 of section SA2 of theswitch, conductor 18, output of amplifier A2, conductor I9, bridgemember I4" of the switch, conductor 82, bridge member I4 of section SAsof the switch, conductor 83, output of amplifier A1, conductor 84,bridge member I4 of section SA; of the switch, conductor 85 and antenna3. It will thus be seen that the outputs of all of the amplifiers areconnected in series.

Anode potential for operation of the different amplifiers is obtainedfrom the rectifier 5 through a circuit comprising conductor 88,resistance 81, modulation reactor 88, conductor 89, and thence throughbridge members I5 of each of the different sections SAl, SA2, and SA; tothe different amplifiers, this connection for the amplifier SAlcomprising conductor 92 which extends to an intermediate point on aseries of resistances 93 connected between the two anodes of thedischarge devices 64.

Grid bias for the different amplifiers is supplied from a suitable biassource represented by the rectangle 6 to a common bias bus 94, the biasconnection from this bus to each of the amplifiers extending throughbridge member I5" of the respective section of the switch, thisconnection for the amplifier A1 comprising conductor 85, resistance 96and inductance 91 to the midpoint of grid inductance 65 of theamplifier.

It will thus be seen that the grid connections to each amplifier extendthrough the contacts controlled by the cross-arms I6 of the respectiveswitch section. The output circuits are controlled by the cross-arms I4,and the connections for supplying operating potentials are controlled bythe cross-arm I5.

If a section of the switch corresponding to one of the amplifiers A1,A2, A3 be rotated to a position such that its bridge members I4, I5, I6engage contacts a and 1, whereas the bridge members I4", I5, and I6"engage contacts (1 and c, then the following changes in the circuits areeffected. The output circuit 2 of the exciter is disconnected from therespective amplifier. The grids of the respective amplifiers aregrounded at the contacts I and c of the right-hand bank of therespective section of the switch through conductors I2 and 69respectively. The output circuit of each of the amplifiers isdisconnected from the remainder of the apparatus at contacts 17 and e ofthe left-hand bank of the switch and a short circuit comprisingconductor 98 extending between contacts I and c of the respective bankis substituted in the antonna circuit in its stead. The anode circuitfor the respective amplifier is interrupted at contact b of the middlebank of the respective. section of the switch, and the anode is groundedat contact 1 of that bank. The grid bias circuit is interrupted atcontact e of this bankof the switch and the grids of the dischargedevices are grounded at contact thereof.

Thus it will be seen that with any section of the switch correspondingto one of the amplifiers A1, A2, and A: rotated to the positionpreviously referred to, the corresponding amplifier is completelyremoved from its operating circuit relation with the other units, itsgrids and anodes are grounded, and an operating connection completed forthe remaining units.

Modulator circuits Now considering the sections of the switchcorresponding to modulators M1 and M2, these modulators are likewiseshown to be of the pushpull type, each comprising a pair of dischargedevices I02. The grid circuits of these discharge devices are controlledby bridge members I6 and I6, the grid of the upper discharge device I02being connected to the input transformer I03 of the respective modulatorthrough bridge member I6 and the grid of the lower discharge devicebeing connected to the input transformer through bridge member IS. Theoutputs of these modulators are connected in series in the circuitextending from the left-hand terminal of the modulation reactor 88through bridge member I4 of section SM1 of the switch thence throughoutput coil I04 of modulator M1, bridge member I4", conductor I05,bridge member I4 of switch section SM2, output I06 of modulator M2,bridge member I4", and condenser I01 to ground, it of course beingunderstood that the opposite end of the modulation reactor 88 is alsogrounded for signal currents.

Anode potential for operation of the different modulators M1 and M2 issupplied from rectifier through conductors 86 and I08, and thencethrough bridge member I5 of section SM1 to modulator M1 and bridgemember I5" of section SM2 to modulator M2. Bias potential for theoperation of the modulators is not supplied through the switch but issupplied from a common modulator bias bus IIO which extends to the biassource 6.

If one of the sections SM1 or SM2 be rotated from the position shown toits alternate position, it will be observed that the circuit of theinput transformer of the respective modulator is interrupted at contactse and b of the respective section of the switch and the grids of thismodulator are grounded at contacts c and f of this bank. The circuit forsupplying anode potential to the modulator is interrupted at contact eof the middle bank of the respective section of the switch and theanodes of the modulator are grounded at contact c of this bank. Theoutput transformer I04, or I05, is disconnected at contacts I) and e ofthe left-hand bank of the respective section of the switch and insteadthereof a short circuit comprising conductor I09 extending betweencontacts c and j of this bank is substituted in the series modulatorcircuit in its stead thereby to complete the operating circuitconnection to the other modulator.

It will of course be understood that the circuits indicated in therectangles A1 and M1 are incomplete and illustrated only with suchdetail as to present a full understanding of my present invention.

Control circuits To effect the desired control of the switch in responseto faults in any of the different apparatus units, certain controlcircuits are provided, these control circuits including a pair of maincircuit breakers H2 and H3 whereby, among other things, the applicationof power to the rectifier 5 is controlled. This rectifier 5 may be ofany suitable type, but preferably is one of the polyphase type having analternating current supply circuit, which I have conventionallyindicated on the drawings by the single line conductor H4, which extendsthrough armature H5 of circuit breaker II 2 when in its upper position,and armature I I6 of circuit breaker H3 when in its upper position tosource II? of polyphase alternating current. These circuit breakerstogether with the Thrustors I1 and 42 are all controlled in response tocertain protective relays in the different apparatus units, andthroughout the equipment. These relays comprise, for example and amongothers, relays I22 in the circuits of each of the amplifiers, only thecontacts thereof being shown in amplifiers A2 and A3; relays I23 inmodulators M1 and M2, only the contacts thereof being shown in modulatorM2; and relay I24 in high power audio amplifier 9. These relays are allconnected in the anode circuits of the different discharge devices andrespond to a current of abnormally largemagnitude to attract theirarmatures to positions opposite to those shown in the drawings. Thereare a large number of additional switches, relays and interlocks wherebythe main circuit breakers H2 and H3 are controlled as will presently beexplained.

To effect the desired selective operation of the switch in response tofaults in the different apparatus units and at the same time to avoidoperation of the switch in response to faults of a merely transientcharacter, a group of control relays is provided for each section of theisolation switch, this group of control relays being represented at thelower portion of Fig. 3 of the drawings by the rectangles bearing thereference characters of the apparatus units to which they correspondpreceded by the letter C. These groups of relays CA1, CA2, CA3, CM1,CM2, are identical in construction and the circuit details of only one,namely, CA1 are illustrated on the drawings. These units bring about thedeenergization of all of the apparatus units in response to a fault of apersistent or repeated character in any apparatus unit, the isolation ofthe apparatus unit in which the fault occurred and reenergization andreconnection of the remaining units in operating circuit relationthereby to permit the transmitter to remain in service with reducedpower output.

An additional system of control relays represented by the parallelogramC corresponding to the main rectifier 5 and audio amplifier 9 is alsoprovided, this system of control relays being similar to thatrepresented by the other rectangles of Fig. 3 but is not arranged tobring about the isolation of any unit. This is by reason of the factthat this group responds to faults in apparatus units essential to anyservice of the transmitter. The function of this group of relays is toremove power from the transmitter, upon the occurrence of certain faultsin the audio amplifier or rectifier, or upon the occurrence of certainother conditions incompatible with operation of the transmitter.

All of the relay groups shown in Fig. 3 are arranged to respond toconditions in a single series control circuit which I shall nowdescribe. This circuit extends from the positive side of a source ofpotential at the lower terminal of the winding of relay I25, throughwinding of relay I25, armature 47 in its upper position, conductor I26,relay I2'I in control unit CA1, conductor I28, thence through a similarrelay in each of units CA2, CA3, CM1, CM2, in series to conductor I29,winding of relay I21 in relay group C, lower contacts of relay I32 ingroup C, on switch I33, off switch I33, conductor I34, contacts of timedelay relay I35 and a series of contacts I36, I31, I38, etc. to ground.

The winding of each of the different relays I2I in the different relaycontrol units is normally short-circuited through a circuit whichincludes desired series connected protective switches. This circuit inshunt with relay I2I of relay unit C comprises conductors I29 and I42,contacts of modulator bias protective relay I43, lower contacts of audioamplifier overload relay I24, conductor I44, contacts of amplifier biasprotective relay I45, conductor I45, a group I4! of series connectedcontacts in rectifier 5, conductor I48, contacts of audio amplifier biasprotective relay I49, conductor I52, and an additional group of contactsor switches I53 back to the opposite terminal of the winding of relayI27 of group C.

It will be noted that the bias protective relays I43, I45 and I49 areconnected directly between the respective bias supply conductor andground whereby these relays are normally energized but are deenergizedupon removal of bias voltage such as might injure an apparatus unit towhich bias from the respective conductor is supplied. The contact groupM1 in the rectifier 5 may comprise any desired number of overloadrelays, either alternating current or direct current, an emergencyshutdown switch, door interlocks, or any desired device in response towhich it is desired that the apparatus should be shut down. Similarlythe contact group I53, which may be arranged upon the control panel maycomprise a door interlock, certain overload relays, emergency shutdownswitch, and any additional switches which open upon a conditionincompatible with continuance of service of the apparatus.

The short circuit across relay I2I for group CA1 will also be traced.This circuit extends from conductor I26 through two groups of seriescontacts I54 and I55, normally closed contacts on relays I22, conductorI56, normally closed contacts on relay I51 to the opposite side of thewinding of conductor I21. The groups of contacts I54 and I55 maycomprise door interlocks corresponding to the respective amplifier,temperature relays responsive to the cooling system of the differentamplifiers, water flow interlocks, or additional over load relays ifadditional discharge devices be employed, or any other switch responsiveto a fault in the particular apparatus unit A1 in response to which itis desired to isolate that unit from the other units and remove it fromservice.

It is necessary to operation of the apparatus that this series controlcircuit comprising the short-circuits across relays I2! shall becontinuous from ground at the right-hand contacts of switch I 38, topositive voltage at the lower terminal of the coil of relay I25, therebyenergizing relay I25. If any one of the switches previously referred toas connected in the branches shorting the relays of winding I2'I beopened.

the corresponding relay I21 becomes energized which in turn causesoperation of the corresponding group of control relays to perform itsdesired protective function.

In addition, if any of the switches I36, I31, I36 opens, power isimmediately removed from the transmitter and cannot be reapplied so longas any one of these switches is open. Relay I is a time delay relay, thewinding of which is connected in shunt to the cathode supply to the"rectifier 5 and the contacts of which close only after these cathodeshave been heated to a desired operating temperature, which may requirean interval of a half hour, for example. Its purpose is to preventapplication of anode volt age to the equipment during this interval.Switches I36, I31 and I38 represent desired water temperature andflowinterlocks for the different discharge devices, door interlocks, or anyother switch which opens in response to a condition incompatible withfurther operation of the transmitter.

Operation A further understanding of my invention may now best be had byreference to its operation. The apparatus is shown in its normaldeenergized condition. Let us suppose that switch II9 is operated to itsclosed position to supply filament power to the rectifier 5. The windingof relay I35 is then energized, which after a predetermined timeoperates to close one break in the previously traced series controlcircuit, this time being suflicient to permit the filaments of therectifiers to heat. Certain additional control operations by theoperator, which are not related to my invention, may also be necessaryto place the apparatus in condition, but assuming that these operationshave been effected, the trans mitter may then be placed into service byoperation of the switch I33 thereby completing the series controlcircuit previously traced, and causing the energization of relays I25and I58 in parallel, the latter winding being energized through thelower contacts of main circuit breaker II2. Relay I56 operates andenergizes the winding of circuit breaker I I2, which in turn operatesall of its armatures to the upper position. Alternating current power isnow supplied from the alternating current source II1 through resistanceI64 to the alternating current bus H4 and rectifier 5. By means of itsupper contacts and conductors I34 and I circuit breaker II2short-circuits the switch I33. The circuit of relay I58 is broken by thelower contacts of circuit breaker II2, a circuit for relay I68 iscompleted, which relay operates and prepares a trip circuit for circuitbreaker II2, a break is produced by contact H5 in the circuit of latchmagnet 39, and an indicator lamp I66 is lighted.

Relay I25 operates and by means of its upper contacts completes acircuit for plus voltage through armature I62 on circuit breaker H3 inits lower position and winding of relay I63. Relay I63 operates andcompletes the closing coil circuit for circuit breaker II3 which in turnenergizes and latches itself closed thereby shortcircuiting the resistorI64. This resistor is provided for the purpose of limiting the startingtransient current in the power supply circuit. This breaker also opensthe circuit of relay I63 causing deenergization of that relay, preparesa circuit for trip coil I15, and energizes an indicator lamp I61. Poweris now supplied to all of the different apparatus units and thetransmitter is in normal operation.

In the event that any contact in any of the branch circuits shuntingrelays I21 be opened for any reason, relay I25 is immediatelydeenergized. The winding of relay I25 and the resistance in shunttherewith, however, pass sufiicient current to energize the moresensitive relays I21 in the control relay groups with the result thatthe corresponding latter relay operates, Considering first the efiect ofrelay I25, this relay I25 by means of its lower contacts applies groundto trip circuit conductor I69 thereby energizing relay I12 and trip coilI13 of circuit breaker II2 through the contacts of relay I68. Sincerelay I58 is deenergized, the closing coil of circuit breaker H2 isdeenergized, with the result that this circuit breaker opens in responseto energization of its trip coil I13. Its contacts I14 then complete acircuit for trip coil I15 of circuit breaker II3, the closing coil ofwhich was deenergized by relay I63. Thus this circuit breaker also opensand all of the apparatus units are deenergized.

This tripping of the circuit breakers is sufficiently rapid for allfaults except certain overload conditions. To protect against theseoverload conditions quick acting direct current protective relays I22,I23, I24 in the amplifiers and modulators, and additional alternatingand: direct current relays in the rectifier 5, the armature of one ofwhich is indicated at I50 are provided with a pair of normally opencontacts. These contacts are arranged, when closed, to connect conductorI69 to ground thereby to energize trip coil I13 exactly as was done byrelay I25, but in more rapid response to the overload. Thus the tripcircuit conductor I69 is grounded by relays I22, I23, I24 and also byrelay I25. The latter relay serves as a check on the first mentionedrelays to assure that the trip circuit conductor is grounded.

Thus opening of any contact in the series protective circuit trips themain circuit breakers. In the event that the fault be an instantaneousone, or one of duration less than a predetermined interval, such as 5seconds, the circuit breakers are again closed when the fault clears andthe respective contact in the protective circuit, which was openedthereby, closes. This, of course, causes energization of relays I25 andI58 which operate as before to close the main circuit breaker.

To describe the operations which occur in response to relays I 21 let usfirst refer to relay group C.

The energization of relay I21 in response to the fault closes a circuitwhich extends from plus voltage through the contacts of relay I16,contacts of relay I11, conductor I18, upper contacts of relay I21,middle armature of relay I19 in its lower position, lower contacts ofrelay I19 and the winding of relay I8I. This relay requires 5 seconds toclose its contacts and since it is assumed that the fault cleared inless than 5 seconds, this relay does not operate. The winding of relayI80, however, is energized in parallel with winding of relay I8I. Thisrelay operates and by its lower contacts completes a holding circuit foritself through the contacts of relays I11 and I16. By means of its uppercontacts it prepares a circuit for the winding of relay I19. Thiswinding is energized when the fault clears and relay I21 deenergizes,the circuit being through the contacts of relays I16 and I 11, lowercontacts of relay I21, upper contacts of relay I80, and winding of relayI19. Relay I19 then energizes and completes a holding circuit for itselfthrough its lower arma- III) III)

ture in its upper position and the contacts of relays I11 and I16. Byits upper contacts it completes a circuit for the winding of relay I 11through the contacts of relay I I6. Relay I I1 is slow acting andrequires approximately 1 minute before its contacts open. If no furtherfault occurs within this period of 1 minute the contacts of relay I"open at the end of that period, thereby deenergizing relay I19 whichoperates and, in turn, causes the deenergization of relays I88 and I8Ithereby restoring all of the relays to normal.

If a second fault occurs within the period of 1 minute, however, acircuit is completed by relay I21, which extends from plus voltagethrough the contacts of relays I16 and I'll, upper contacts of relayI21, middle armature and upper contacts of relay I19, winding of relayI32 and switch I83 which is normally in its closed position. Relay I32then operates, completing a holding circuit for itself through its uppercontacts and by its lower contacts permanently opening the seriesprotective circuit, thereby preventing any further automatic applicationof power to the equipment. That is, power is now locked off.

After the fault has been cleared, however, the operator may again applypower to the equipment by operating switch I83 to the open posit on,thereby deenergizing relay I32 which closes its lower contacts. Theequipment may now be placed in service byclosing switch I33.

Relay I32 would also have become energized had the first fault whichoccurred been of a duration greater than 5 seconds, thereby causing theoperation of time delay relay I8I, the contacts of which directlyenergize the winding of relay I32 through the contacts of relays I11 andI16, thereby causing the series protective circuit to be opened.

The efiect of ofi switch I33, on switch I33 and automatic switch I83 maynow be better understood. Switch I33 is biased to the closed positionand is used to stop the transmitter. Switch I33 is biased to the openposition and is pressed to the closed position to start the transmitter.Switch I83 remains in either position to which it is operated. If switchI33 be pressed to start the transmitter it becomes short-circuited bvthe upper contact on circuit breaker I I2, when that circuit breakercloses. If automatic switch I 83 be open any fault causes thetransmitter automatically to shut down. If automatic switch I 83 beclosed, power is removed only for the duration of the fault unless thefault be of the continuous or recurrent type previously referred to,when power is permanently locked off bv relay I32. To shut down thetransmitter, off switch I33 may be pressed. This opens the seriesprotective circuit causing circuit breaker II 2 to open thereby removingthe short circuit from switch I 33. Thus when switch I 33' is releasedthe series protective circuit is open at the contact of switch I33. Instarting the transmitter switch I83 should first be opened to deenergizerelay I32, if then energized.

It will be noted that each of the parallelograms CA1, CA2, CA3, CM1,CM2, and C are divided into two rectangles by the dotted line. Therelays in the lower of the two rectangles operate in exactly the sameway as has been described in connection with group C. In place of therelay I32 of the upper rectangle representing group C two relays I85 andI86 are employed in the upper portion of the rectangles CA1, CA2, CA3,CM1, CM2, and connected to control the isolation switch.

The windings of these relays are energized through a switch I81 inresponse to a fault in the respective unit of greater than the durationdetermined by the relay I SI of the respective group, or to two faultswithin an interval determined by relay II'I of the respective group.Relay I86 is quick acting and immediately deenergizes lamp I88 and bymeans of its lower armature establishes a holding circuit for relays I85and I 86. By means of its armature I89 it completes a circuit extendingfrom ground through said armature I89, conductor I92, auxiliary switch29 of section SA1 of the isolation switch, conductor I 93, latch magnet39 and armature II5 of circuit breaker II2 to the positive side of thesource of potential. Latch magnet 39 is now energized and by means ofarmature 41 opens the series protective circuit. This assures againstany operation of the isolation switch with power applied to thetransmitter. Armature 4'! also bridges contacts I94 to prepare a circuitfor rotator II. Armature 46 opens the power supply circuit for exciter Ithereby removing excitation from amplifiers A1, A2, and A3. The latchmagnet also lifts the latch 36 thereby releasing the-- cam 34 whichstarts its counterclockwise rotation under influence of spring 32.

Relay I86 also by means of its upper contacts connects ground throughconductor I95 to the rotor I 'I of switch section SA1. longitudinalmovement of the shaft I3 sufficient to release its movable contacts fromthe stationary contacts, auxiliary switch 52 closes completely thecircuit for the rotator through conductor I96, and switch 52 to positivepotential at the middle contacts I94 of the switch Relay I85 has twopairs of contacts, the upper pair of which is normally closed, quick toopen, and slow to close, the lower pair of which is normally open, quickto open, and slow to close. This is represented by time delay devices I91 and I98 attached respectively to the movable contacts, these contactsbeing indicated as connected by means of springs I99 and 202 to oppositeends of a reciprocating core in the winding. The time delay devicesretard the movement of the contacts only in one direction as indicatedby the arrows and hence upon energization of the winding the uppercontacts quickly open and the lower contacts slowly close, and ondeenergization the lower contacts quickly open and the upper contactsslowly close. It will be understood, however, that this showing of thisinstrumentality of the system is but schematic and symbolic and forpurposes of explanation only. Any suitable device may be employed forthe purpose. The upper contacts are connected in the shunt protectivebranch corresponding to amplifier A1 and thus this branch is now heldopen by relay I85. The lower contacts are connected in shunt with thewinding of relay I 21 and the interval required for closing of thesecontacts is sufliciently great to assure that relay I88 has time tooperate its contacts and to permit operation of latch magnet 39 tooperate armatures 46 and 41.

The rotator Il no-w rotates switch section SA1 to its alternateposition. At the beginning of this movement armature 28 makes a break inthe circuit of main Thrustor 42. Armature 29 opens the circuit of latchtrip magnet 39 thereby causingthe latch to fall upon the cam. Just priorto completion of this movement armature 21 again closes the break in thecircuit of main actuating mechanism 42 and armature 29 bridges its uppercontacts to prepare a circuit through conductor After a slight 203 tocontrol group CA1 for a purpose later to be described. When the cam 34has almost completed its counterclockwise motion auxiliary switch 51closes thereby completing a circuit from plus voltage through switch 51,main Thrustor 42, armature 21, which is now in its upper position, andarmature 28 of each of the other switch sections to ground. The mainThrustor now operates the cam 34 in. a clockwise direction thereby againmoving shaft I2 to the left and closing all of the switches. Just beforeit completes this movement switch 52 opens thereby deenergizing therotator I1 and when thi movement is finally completed latch 31 drops,locking the cam in the position shown and switch 51 opens, deenergizingthe main Thrustor. Simultaneously switches 46 and 41 close, switch 46again energizing exciter 5 and switch 41 closing the series protectivecircuit. Switch section SA1 is now retained in the position to which ithas been actuated by friction between its stationary and movablecontacts. Amplifier A1 is now disconnected from the system, and sincethe lower contacts of relay I are closed thereby short-circuiting therespective branch of the series protective circuit, this circuit becomescompleted as soon as armature 41 engages its upper contacts. Relays I25and I58 immediately close the circuit breakers, thereby applying powerto the remainder of the equipment. The transmitter now is againenergized for operation with the exception that the amplifier A1 isdisconnected and deenergized. The signal voltage, however, which issupplied to the modulator is now reduced, this having been. effected byarmature 189' of relay I86 which causes the energization of relay 288through an obvious circuit.

This relay operates and inserts in the input circuit of the amplifier 8an attenuation pad thereby to reduce the applied signal voltage.Obviously, the voltage applied to the antenna is now also reduced.

It will, of course, be understood that the same operation. occurs inconnection with each of the other amplifiers, or modulator units wherebyany one or more of these units may be automatically removed from servicein response to a sustained or repeated fault therein.

The time required for operation of the isolation switch and during whichthe transmitter is deenergized, i. e. off the air, may be in the orderof four seconds. Thus the service of the transmitter, for all purposesof the broadcast listener, is continuous even though faults occurrequiring isolation of certain of the apparatus units.

It sometimes happens in the operation of the transmitter that it isdesirable to shut the transmitter down completely, the control circuitsbeing deenergized, and then again to replace the transmitter in servicewith the isolation switch in the same condition in which it was prior tothe shutdown. When the control circuits are deenergized relays I85 andI86 corresponding to an isolated unit are actuated to the deenergizedposition. To energize these relays corresponding to an isolated unit,when the transmitter is again put in service, the upper contacts,cooperating with armature 29 in. the different switch sections, andconductors 283 and 288 are provided, the latter being connected topositive potential. Thus when voltage is again applied to conductor 2%it is supplied through armature 29 of an isolated unit and conductor 283to the windings of relays. I 85 and I86, whereby these relays are againenergized.

An isolated unit may again be restored to service by operating switchI81 to its lower position. This switch deenergizes relays I85 and I85and by means of its lower contacts connects ground to conductor I93thereby again energizing the latch trip magnet. This, of course,initiates the cycle of operations of the main Thruster but since relayI86 corresponding to the isolated unit is deenergized, the rotator ofthat unit is likewise deenergized. Accordingly,' as soon as pressure isreleased between the stationary and movable contacts of the isolatedswitch section, that section returns under influence of the bias of theThrustor aided by spring 45 to the normal position. Upon substantialcompletion of this motion the main Thruster is again energized and allof the switches are closed.

If it be desired manually to isolate any particular apparatus unit eventhough that unit be in serviceable condition, this may be effected bypressing switch 284. This switch energizes the windings of relays I85and I86 which in turn brings about the isolation of the correspondingunit in the manner already described.

It will be noted that a relay 201 is connected in shunt with the relaysI85 and I86 of apparatus unit CA1 and a similar relay is connected inshunt with relay I32 of unit C. These relays energize when thecorresponding relays with which they are in shunt become energized, andwhen operated energize a lamp 288. These lamps may, of course, belocated as desired, as for example, within the housing of the isolatedapparatus unit thereby to illuminate that particular unit.

It sometimes happens that a fault in one of the amplifier or modulatorunits may produce an overload in the rectifier unit 5, which overloadwould be removed upon isolation of the amplifier or modulator unit inwhich the fault occurred. If, however, the overload relays of unit 5operate in response to such a fault therein and cause operation of therelay group C, power will be locked oiT from the equipment by relay I32in the manner that has already been described. This is undesirable andto avoid it relay I16 is employed, this relay being connected betweenconductors I26 and I29 and hence in shunt with all of the protectivebranches corresponding to units to be isolated. Thus this relay isshortcircuited except when a fault occurs in one of the units capable ofisolation. When this occurs relay I16 becomes energized and opens theenergizing circuit for all of relays I11, I19, I88, I8I,

and I 32 in the control group C. Thus this group is disabled during theperiod in which isolation of any apparatus unit is being effected by theother control units CA1, CA2, CA3, CMI, CMz.

On the drawings immediately above each of the auxiliary switch groups21, 28, 29, is shown a switch 289. These switches represent doorinterlocks on the housing of the different units capable of isolation.All of these switches are normally closed, connected in series, andarranged to control the bias source 6. This source, for example, maycomprise .a plurality of motor generator sets, each of which supplies acorresponding bias bus 94, III], 2I0 with voltage of suitable value. Theexciting windings of these generators are represented by the element 2II in the rectangle 6, this element being shown as connected between plusvoltage and ground through the different door interlocks 209. When aunit has been isolated the auxiliary switch 28 of the respective switchsection short-circuits the corresponding door interlock. Thus thecompartment occupied by the isolated apparatus unit may be enteredwithout affecting the operating units.

The relay groups shown in the lower rectangles respectively controlunits C, CA1, CA2, CA3, CM1, CM2, may conveniently be mounted onindividual panels and arranged for plug and jack connection with therest of the apparatus. These units may then be removed for repair whilethe remaining equipment is in service and without affecting any of theremaining equipment. Care should be taken, however, when any such relaygroup is removed, to open switch I83, thereby to avoid successiveoperation of the main circuit breakers in response to a fault in theunit corresponding to the removed group. This may occur by reason of theshort circuit across switch I33 if switch I83 be closed.

In the drawings the different isolation switch sections are shown byidentical symbols. It may occur, however, in connection with the gridcircuits of the modulators, for example, that to shorten the leads, theswitch necessary to alter the modulator connections should be locatedsomewhat closer to the modulator unit than the isolation switchstructure can be placed. This may readily be effected by utilizingconventional knife blade switches in the apparatus unit and operatingthis switch from the sleeve of the respective switch section through asuitable lever arrangement.

It will be understood that while I have described my invention withparticular reference to a high frequency transmitter, that its utilityis in nowise limited to such application, and that I contemplate its usegenerally in connection with multiple unit electrical apparatus.

While I have shown a particular embodiment of my invention it will beunderstood that I am not to be limited thereto since it is capable ofmany modifications both in the circuit arrangement and in theinstrumentalities employed. I contemplate by the appended claims tocover any such modifications as fall within the true spirit and scope ofmy invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. The combination, in a multiunit electrical apparatus, of meansconnecting the different units of said apparatus in operating circuitrelation with each other, additional means to energize each unit, meansresponsive to a fault in any unit for deenergizing all of said unitswhile maintaining the connection of said units in circuit relation witheach other, and means responsive to continuation of said fault for morethan a predetermined interval to disconnect the unit in which said faultoccurred from operating circuit relation with the other of said units.

2. The combination, in a multiunit electrical apparatus, of meansconnecting the different units of said apparatus in operating circuitrelation with each other, additional means: to energize each unit foroperation, means responsive to a fault in any unit for deenergizing saidunit while maintaining the connections of said units in circuit relationwith each other, and means responsive to recurrence of said fault withina predetermined interval to disconnect the unit in which said faultoccurred from operating circuit relation with the other of said units.

3. The combination, in an electrical apparatus comprising a plurality ofoperating units connected together for operation, of switching meanswhereby any of said units may be disconnected from the other of saidunits and the other of said units reconnected for operation, and meansresponsive either to continuation of a fault for more than apredetermined interval, or to occurrence of more than a predeterminednumber of faults within a predetermined interval in any unit to operatesaid switching means to disconnect the unit in which said fault occurredfrom said other units and subsequently to reconnect said other unitstogether for operation.

4. The combination, in an electrical apparatus comprising a plurality ofoperating units connected in circuit relation to each other, of meansresponsive either to continuation of a fault in any unit for more than apredetermined interval, or to occurrence of more than a predeterminednumber of faults therein within a predetermined interval, to disconnectthe unit in which the fault occurred from the other of said units and tomaintain in operating circuit relation the other of the units of saidapparatus.

5. The combination, in an electrical apparatus comprising a plurality ofoperating units connected in circuit relation to each other, of meansresponsive to a fault in any unit to deenergize all of said units forthe duration of said fault,

and to reenergize said units in response to removal of said fault andmeans responsive to continuation of said fault beyond a predeterminedtime interval to prevent reenergization of the unit in which said faultoccurred and to permit reenergization of the other of said units by saidfirst means.

6. The combination, in an electrical apparatus comprising a plurality ofoperating units connected in circuit relation to each other, of meansresponsive to a fault in any unit to deenergize all of said units forthe duration of said fault, and means responsive to repetition of saidfault within a predetermined time interval to prevent reenergization ofthe unit in which said fault occurred and to permit reenergization ofthe other of said units.

7. The combination, in an electrical apparatus, of a plurality ofoperating units connected in operating circuit relation to each other,an additional unit common to said first units, the operation of saidfirst units being dependent upon the operation of said additional unit,and means responsive to a fault in any of said units to deenergize allof said units for the duration of the fault, to reenergize said unitsafter termination of said fault if it be of less than a predeterminedduration, and to prevent reenergization of all of said units if saidfault be in said additional unit and continuous for more than apredetermined interval.

8. The combination, in an electrical apparatus, of a plurality ofoperating units connected in operating circuit relation to each other,an additional unit common to said first units, the operation of saidfirst units being dependent upon the operation of said additional unit,means responsive to a fault in any of said units to deenergize all ofsaid units for the duration of the fault, means to deenergize all ofsaid units in response to termination of the fault, and means to preventreenergization of the unit in which the fault occurred if it be in Oneof said first units and of greater than a predetermined duration.

9. The combination, in an electrical apparatus, of a plurality ofoperating units connected in operating circuit relation to each other,an

additional unit common to said first units, the operation of said firstunits being dependent upon the operation of said additional unit, meansresponsive to a fault in any of said units to deenergize all of saidunits for the duration of the fault and to reenergize said units inresponse to termination of said fault, and means responsive torecurrence of said fault within a predetermined interval if said faultbe in one of said first units to isolate said one unit from operatingcircuit relation with the other units.

10. The combination, in an electrical apparatus, of a plurality ofoperating units connected in operating circuit relation to each other,an additional unit common to said first units, the operation of saidfirst units being dependent upon the operation of said additional unit,and means responsive to a fault in any of said units to deenergize allof said units for the duration of the fault, to reenergize said unitsafter termination of said fault if it be of less than a predeterminedduration, and to prevent reenergization of all of said units if saidfault be in said additional unit and recurs within a predeterminedinterval.

11. The combination, in an electrical apparatus comprising a pluralityof units connected in operating circuit relation, of a power supply unitcommon to said other units, means responsive to a fault in any of saidoperating units to remove the unit in which the fault occurred fromoperating circuit relation with the other of said units and to maintainthe other of said units in operation, means responsive to a faultcondition in said power supply unit to deenergize all of said operatingunits, and means to prevent operation of said last means in response toa fault condition in said power supply unit created by a fault in one ofsaid operating units.

12. The combination, in a high frequency apparatus, of a plurality ofelectron discharge devices, a unitary switch structure includingswitching means connecting the output circuits of said discharge devicesin operating circuit relation, and to supply operating potentials to theelectrodes of said discharge devices, means responsive to faults in anyof said discharge devices to deenergize all of said discharge devices,means responsive to said fault only if it be of predetermined characterto disconnect said discharge device from the other of said dischargedevices and to then reconnect the other of said discharge devices inoperating circuit relation.

13. The combination, in a high frequency apparatus of a plurality ofamplifiers, power supply apparatus for said amplifiers, a unitary switchstructure extending in proximity to all of said amplifiers, said unitaryswitch structure including switching means connecting all of saidamplifiers in operating circuit relation and to supply operatingpotential from said power supply apparatus thereto, means responsive toa fault in any of said amplifiers to deenergize said power supply unit,and means responsive to certain of the faults to which said last meansresponds to operate said unitary switch structure to disconnect all ofsaid amplifiers from each other and then to reconnect said amplifiersother than the one in which the fault occurred for operation while theamplifier in which the fault occurred remains deenergized.

14. The combination, in a high frequency apparatus of a plurality ofamplifiers, power supply apparatus for said amplifiers, a unitary switchstructure extending in proximity to all of said amplifiers, said unitaryswitch structure including switching means connecting all of saidamplifiers in operating circuit relation and to supply operatingpotential from said power supply apparatus thereto, means responsive toa fault in any of said amplifiers to deenergize said power supply unitfor the duration of the fault and then to reenergize said power supplyapparatus, means selectively responsive to certain of said faults tooperate said unitary switch structure, while said power supply apparatusis deenergized, to disconnect the amplifier in which the fault occurredfrom the other amplifiers and to reestablish operative connections forthe other of said amplifiers before said power supply apparatus is againenergized.

15. In combination, a plurality of high frequency amplifiers connectedin circuit relation with respect to currents amplified thereby, means toenergize said amplifiers for operation, means responsive to a fault inany of said amplifiers to deenergize all of said amplifiers, and meansoperative in response to said fault only if it be of predeterminedcharacter, to disconnect the amplifier in which the fault occurred fromsaid circuit relation with the other amplifiers with respect toamplified currents and to reconnect the other amplifiers in circuitrelation with respect to currents amplified thereby.

16. In combination, a. plurality of high frequency amplifiers connectedin circuit relation with respect to currents amplified thereby, means toenergize said amplifiers for operation, means responsive to a fault inany of said amplifiers to deenergize all of said amplifiers and 'toreenergize said amplifiers after removal of said fault unless said faultcontinues for more than a predetermined interval, and means operativeupon continuation of said fault for more than said predeterminedinterval to disconnect the amplifier in which the fault occurred fromthe other amplifiers while said amplifiers are deenergized, and to thenreenergize said other amplifiers.

17. In combination, a plurality of high frequency amplifiers connectedin circuit relation with respect to currents amplified thereby, means toenergize said amplifiers for operation, means responsive to a fault inany 'of said amplifiers to deenergize all of said amplifiers and toreenergize said amplifiers after removal of said fault, and meansresponsive to occurrence of a fault more than a predetermined number oftimes within a predetermined interval in any amplifier to disconnect theamplifier in which the fault occurred from the other amplifiers whilesaid amplifiers are deenergized and to then reenergize said otheramplifiers.

18. The combination, in a. high frequency transmitter adapted foroperation with a predetermined power output, of means to supply signalcurrents to said transmitter for transmission thereby, means responsiveto a fault in said transmitter to connect said transmitter for operationat less than said predetermined power output, and to produce acorresponding reduction in the intensity of said signal currentssupplied to said transmitter.

GEORGE W. FYLER.

54:} CERTIFICATE OF CORRECTION. I

Patent No. 2,15z,LL72. March 2 1959.

., GEORGE w. FYLER. I

It is hereby certified that error appears in the brinted specificationof the above numbered patent requiring correction as follows: Page 2,second column, line 15, for the patent number "7,95 5,152" read 1,955,Lq2; page 9, second column, line 67, claim8, for "deenergize" readreenergize; and that the said Letters Patent should be read with this.correction therein that the same 'may conform to the record of the casein the Patent Office.

Signed and sealed this 16th day or May, A. D. 1959.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

5 0 7 CERTIFICATE OF CORRECTJ ION. V I

Patent No. 2,152,1fl2. March 2 1959.

.. GEORGE w. FILER, i

It is hereby certified that error appears in the iarinted vspecificationoi" the above' numbered patent requiring correction as follows: Page 2,second column, line 15, for the patent number "7,95 5,b.32" read 1,935,1 52; page 9, second column, line 67, cla1m8, for "deenergize" readreenergize; and that the said Letters Patent should be read with this,correction therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 16th day of May, A. D. 1959.

Henry Van Arsdale (Seal) Acting Commissioner of Patents. I

